Multiple element forced air flow air heating furnace



Nov; "11, 1952 e. B. HERBSTER MULTIPLE ELEMENT FORCED AIR FLOW AIR HEATING FURNACE Filed April 6. 1948 n mummy Q I II I] l] I] [I I] I! Patented Nov. 11, 1952 srrrs MULTIPLE ELEMENT FORCED AIR FLOW AIR HEATING FURNACE George B. Herbster, Cleveland, Ohio, assignor, by mesne assignments, to 8600 Denison Company, Cleveland, Ohio, a corporation of Ohio Application April 6, 1948, Serial No. 19,401

8 Claims.

This invention relates to heaters and is an im provement on the heater disclosed in my copending applications, Ser. No. 663,506, filed April 19, 1946, now abandoned, Ser. No. 787,455, filed November 21, 1947, now U. S. Letters Patent 2,564,257 and Ser. No. 827, filed June 7, 1948, now U. S. Letters Patent 2,564,479, both issued August 14, 1951. As more fully described in my U. S. Letters Patent No. 2,564,479, the heat exchanger comprises a plurality of annular heads arranged in a horizontal row in spaced face to face relation to each other thereby defining an axial central passage of uniform diameter extending from one end of the row to the other and defining between adjacent heads radial passages whieh connect at their inner ends to the central passage and which, at their outer ends, are open throughout the greater portion of the peripheral extent of the heads. Further, as described in said last mentioned copending application, the entire heat exchanger including its combustion chamber is enclosed in a suitable casing having a spiral peripheral wall and having side walls with air inlet openings, respectively, which are coaxial with the central passage through the exchanger. For efiecting a fiow of air into the inlet openings and central passage and out through the radial passages and through the casing a rotary centrifugal impeller is provided, the impeller being formed in a plurality of segments arranged one segment between each pair of adjacent annular heads near the outer periphery thereof. All of the segments are carried on a common driven shaft coaxial with the central opening.

While in this structure of my prior application a relatively high eificiency of heat exchange relation between the heat exchanger surface and the air is obtained, such is accomplished at some sacrifice in over-all size of the unit.

Accordingly, it is one of the objects of the present invention to provide a heater of the general character described in my above entitled copending applications in which the heat exchange head is so arranged as to provide a more nearly balanced relation between the area of the external heat exchange surface, the amount of air that can be passed into emcient heat exchange relationship therewith, the area of the internal heat exchange surface, and the amount of heating media that can be passed into eflicient heat exchange relationship therewith, so that a reduction in the over-all size of the unit for a given heating capacity and efiiciency can be obtained.

Other objects and advantages will become apparent from the following description in which reference is made to the drawings in which:

Fig. 1 is a side elevation, partly in section, of a heater embodying the present invention; and,

Fig. 2 is a horizontal sectional view of the heater taken on the line 2-2 of Fig. l.

Referring to the drawings, the heater comprises generally a heat exchanger which is composed of a plurality of annular heads I which are arranged in a row in axial alignment and in spaced face to face relation to each other so as to define a central passage, indicated generally at 2, and radial passages 3, defined by and lying between adjacent annular heads I. The passages 3 connect at their inner ends with the central passage 2 and are open at their outer ends throughout substantially the entire peripheral extent of the heads. Each of the heads has a combustion chamber portion ll and a stack portion 5. Each combustion chamber portion l is open and in communication at its lower end with a common burner compartment 6 in which is located a burner i having a plurality of discharge ports which discharge upwardly toward the combustion chamber portions l respectively. Thus each head including its combustion chamber portion 3 and stack portion 5 is isolated from the others throughout its entire extent except for a slight blocking by the burner compartment top wall and by the accumulating head for the stack portions 5.

The burner heads are enclosed in a suitable casing 6 having a spiral peripheral wall 9 and side wall-s it]. opening it aligned with the central passage 2 of the heat exchanger and coaxial therewith. Mounted on suitable brackets [2 which are secured to the casing 8 is a shaft i3 carrying a pulley it which is driven by a motor it through a suitable belt iii. The shaft I3 is coaxial with the annular heads 8. Mounted on the shaft I3 for rotation therewith are a plurality of rotary centrifugal impeller segments 57 arranged one between each pair of adjacent heads I and one between each end of the row of heads and the adjacent side wall Ill. l he blades of the impeller segments ii are arranged adjacent the outer periphery of the annular heads I and fill the space between adjacent heads and between the side walls Hi and the heads adjacent thereto with slight operating clearance.

The peripheral wall 9, at its shortest radius, lies against or closely adjacent the outer peripheries of the heat exchanger, and progressively recedes outwardly therefrom in the direction of rotation of the impeller segments ii. The casing discharges generally tangentially of the heat exchanger through a discharge portion H3.

The heads, as pointed out in my copending applications, are preferably formed of two sheets of metal joined together at their inner and outer peripheries and provided between their inner and outer radial limits with corrugations such that the passages 3 between adjacent heads form a series of Venturi sections having relatively short throats and relatively long expanding por- Each side wall has an air inlet tions inv a direction radially outwardly of the heads, and the annular heating passages in each head are concentric and adjacent to, but uncommunicated with, each other.

It is apparent from the foregoing description that upon rotation of the impeller air is drawn into the central passage and discharged tbetween the adjacent heads and between the end walls It) and the heads adjacent thereto.

In each of my copending applications, the central openings of the heads are of the same diameter so that the resultant central passage of the exchanger is of uniform diameter throughout its length. Such materially affects the overall size required for a heater of given B. t. u. output.

Since the heads at the ends of the row have central openings adequate to pass the total amount of air to be heated and since part of the air is discharged through each radial passage and the central openings of the heads progressively farther inwardly from the ends therefore need to pass progressively less air, the latter central openings do not function efficiently but do reduce the radiating surface and permit unnecessary localized eddy currents.

The loss of radiating surface can be compen sated for to some extent by increasing the outer radius of the heads but any such over-all increase results in a very marked increase in the cost of the unit. In no event does it provide a balance between the amount of air supplied and the heat exchange surface exposed to the air. Nor can this balance be effected by adding more heads to the row.

In accordance with the present invention, therefore, the heads in the row are provided with different diameter central openings, for example, the outermost heads at the end of the row have large central openings 20, those next inwardly therefrom have smaller central openings 2|, this progressive decrease in the central openings being continuous from the outermost ends of the row to the longitudinal mid-portion of the row, regardless of the number of heads employed in a. particular heater. For example, in the illustrative example, the opening must provide sufficient air for effectively supplying the discharge passage 3 between the end head of the row and the next inwardly adjacent head plus one-half of the air required to supply the next inwardly adjacent passage 3. The opening however, need be only of sufncient diameter to supply one-half the amount of air required for the middle one of the passages 3. As a result the radiating surface of the head I having a passage 2| may be increased appreciably by reducing its central opening, the amount of increase depending upon the number of heads in the row and their spacing from each other.

With this arrangement the resultant central passage is one which is convergent from its outer ends to the longitudinal mid-portion of the row of heads and is of just sufficient diameter at all points along its length to-carry the amount cf air which must be passed therebeyond inwardly endwise of the row. This provides a very substantial gain in heat exchange surface for a given over-all length and diameter of heat exchanger without any sacrifice or diminution in the amount of air supplied to various parts of the exchanger.

The central passage does not have to be contracted at a uniform rate, the diameter at any portion depending upon the amount of air required therebeyond toward the longitudinal midportion. Thus, extraneous limitations or design may require larger heads or wider spacing of the heads at different portions of the exchanger, in which event the proper balance can be maintained by changing the central passage accordingly.

Since the radiating surface of the head having the opening 2| is thus increased, more air can be heated thereby and consequently it may be spaced a little farther from adjacent heads than would be the case otherwise, the change in spacing being balanced against the increase in surface, amount of air, and efiiciency of application of the air. Further flexibility is possible by using impeller vanes of different spacing and pitch for each radial passage and burner ports of different sizes and arrangements for each head. Again, heads of different axial thickness from each other make possible further variations which can be used to maintain the proper balance. Thus the greatest advantage may be taken of all of these correlated but variable factors.

Accordingly, the internal and external heat exchange surfaces, heat distribution, and flow of air to be heated can be brought more nearly into balance with substantially higher efficiency and elimination of hot and cold spots by properly adjusting these various factors. Both the heat exchanger and the air heated thereby can be brought to a more nearly uniform temperature.

Having thus described my invention, I claim:

1. A heat exchanger comprising a plurality of upright generally annular hollow disc-like heating heads, each having a central opening, said heads being arranged in a row in coaxial and spaced face to face relation to each other and thereby providing a central passage and a plurality of generally annular radial passages between the heads leading from the central passage and open at the outer peripheries of the heads, the heads inwardly toward the midportion of the heat exchanger from one end of the row having smaller central openings than the head at said end of the row, each of said heads having a combustion chamber portion at its lower portion and an exhaust portion at its upper portion, the said combustion chamber portion and exhaust portion of each head being spaced apart endwise of the row from the corresponding portions of adjacent heads, each head having a plurality of passages therein extending circumferentially of the heads in opposite directions from its combustion chamber portion to its exhaust portion, burner means operatively associated with the combustion chamber portions of the heads to supply combustible media into the combustion chamber portions, and. blower means operatively associated with the row of heads for causing air to enter the central passages and discharge through the radial passages.

2. The heat exchanger according to claim 1 further characterized in that the central openings of the heads are progressively smaller inwardly endwise of the heat exchanger from said head at said one end of the row.

3. A heat exchanger comprising a plurality of upright generally annular hollow disc-like heating heads, each having a central opening, said heads being arranged in a row in coaxial and spaced face to face relation to each other and thereby providing a central passage and a plurality of generally annular radial passages between the heads leading from. the central passage and open at the outer peripheries of the heads.

the heads at the ends of the row having larger central openings therethrough than the heads therebetween and the openings of successive heads inwardly from the ends toward the axial mid-portion of the exchanger being progressively smaller than the openings of the heads outwardly therefrom toward the nearest end of the exchanger, each of said heads having a combustion chamber portion at its lower portion and an exhaust portion at its upper portion, the said combustion chamber portion and exhaust portion of each head being spaced apart endwise of the row from the corresponding portions of adjacent heads, each head having a plurality of passages therein extending circumferentially of the heads in opposite directions from its combustion chamber portion to its exhaust portion, burner means operatively associated with the combustion chamber portions of the heads to supply combustible media into the combustion chamber portions, and blower means operatively associated with the row of heads for causing air to enter the central passages and discharge through the radial passages.

4. A heat exchanger comprising a plurality of upright generally annular hollow disc-like heating heads, each having a central opening, said heads being arranged in a row in coaxial and spaced face to face relation to each other and thereby providing a central passage and a plurality of generally annular radial passages between the heads leading from the central passage and open at the outer peripheries of the heads, said heads having central openings of different diameters such that the central passage is of decrescent size inwardly of the exchanger from at least one end, each of said heads having a combustion chamber portion at its lower portion and an exhaust portion at its upper portion, the said combustion chamber portion and exhaust portion of each head being spaced apart endwise of the row from the corresponding portions of adjacent heads, each head having a plurality of passages therein extending circumferentially of the heads in opposite directions from its combustion chamber portion to its exhaust portion, burner means operatively associated with the combustion chamber portion of the heads to supply combustible media into the combustion chamber portions, and blower means operatively associated with the row of heads for causing air to enter the central passages and discharge through the radial passages.

5. A heat exchanger comprising a plurality of upright generally annular hollow disc-like heating heads. each having a central opening, said heads being arranged in a row in coaxial and spaced face to face relation to each other and thereby providing a central passage and a plurality of generally annular radial passages between the heads leading from the central passage and open at the outer peripheries of the heads, said heads having central openings of different sizes such that the central passage is of decrescent size inwardly of the exchanger from both ends toward the axial mid-portion of the exchanger, each of said heads having a combustion chamber portion at its lower portion and an exhaust portion at its upper portion, the said combustion chamber portion and exhaust portion of each head being spaced apart endwise of the row from the corresponding portions of adjacent heads, each head having a plurality of passages therein extending circumferentially of the heads in opposite directions from its combustion chamber portion to its exhaust portion, burner means operatively associated with the combustion chamber portion of the heads to supply combustible media into the combustion chamber portions, and blower means operatively associated with the row of heads for causing air to enter the central passages and discharge through the radial passages.

6. A heat exchanger comprising a plurality of disc-like upright generally annular heat exchange heads of substantially the same outer diameter, each of said heads having a central opening, said heads being arranged in a row in coaxial and spaced face to face relation to each other and defining a central passage and a plu-- rality of generally annular radial passages between the heads leading from the central passage and open at the outer peripheries of the heads, said heads having their central openings so related to each other that the central passage is of decrescent diameter from the ends of the exchanger inwardly toward the axial mid-portion thereof, each of said heads having a combustion chamber portion at its lower portion and an exhaust portion at its upper portion, the said combustion chamber portion and exhaust portion of each head being spaced apart endwise of the row from the corresponding portions of adjacent heads, each head having a plurality of passages therein extending circumferentially of the heads in opposite directions from its combustion chamber portion to its exhaust portion, burner means operatively associated with the combustion chamber portion of the heads to supply combustible media into the combustion chamber portions, and blower means operatively associated with the row of heads for causing air to enter the central passages and discharge through the radial passages.

7. A heat exchanger according to claim 1 characterized in that said heads have substantially the same outer diameters.

8. The heat exchanger according to claim 1 characterized in that the radial dimensions of the heads between their inner and outer peripheries are in inverse relation to the radial dimension of the central openings.

GEORGE B. HERBSTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,709,176 Hyde Apr. 16, 1929 1,726,275 Modine Aug. 27, 1929 1,877,905 Le Grand Sept. 20, 1932 2,314,825 Herbster Mar. 23, 1943 2,346,178 Mercier Apr. 11, 1944 2,439,775 Kennedy Apr. 13, 1948 FOREIGN PATENTS Number Country Date 530,879 France Oct. 11, 1921 94,297 Switzerland Apr. 17, 1922 185,531 Great Britain Sept. 14, 1922 228,327 Great Britain Feb. 5, 1925 

